RAT - Sintered Alpha SiC Refractories
Material CharacteristicsSintered alpha SiC is produced by pressureless sintering submicron silicon carbide powder. The sintering process results in a self-bonded, fine-grained (less than 10 micrometers) SiC material that is 98% dense, giving it high durability. It is a single-phase material with no secondary bond phase that can weaken at high temperatures and cause component failure. Additionally, it has outstanding high temperature properties, including oxidation resistance, superior creep resistance and excellent strength.
Application AdvantagesThere are numerous applications for sintered alpha SiC in the ceramic industry, from ceramic belts for sintering furnaces (ceramic and metal) to rolls for roller hearth furnaces to kiln furniture for high temperature firing of products, such as alumina components. Other examples include nozzles, wear tile/liners, thin pins and assemblies for hang firing long tubes, thermocouple protection tubes and heat exchanger tubing, among others.
In these and other applications, sintered alpha SiC provides numerous advantages over other types of refractories. For example, sintered alpha SiC kiln support beams offer low mass design potential and excellent strength, allowing for reduction of beam cross section by 50%. At the same time, the sintered alpha SiC beams offer a 40% reduction in mass (weight) versus traditional refractory SiC materials—without compromising load carrying capacity. This reduced beam volume and weight mean more product per kiln run to maximize furnace productivity and reduce total firing costs. Documented kiln car retrofits with sintered alpha SiC beams have increased productivity over 20% and have shown paybacks of two years and less.**
As another example, similar results can be obtained with sintered alpha SiC ultra-thin, lightweight kiln tiles. The thinner tiles/batts are extremely strong, yet are as thin as 2 mm in smaller sizes, allowing for more useable kiln space and the ability to efficiently load and fire more shippable product with less kiln furniture. Very fast thermal cycling is also possible given the tile’s resistance to thermal shocking and its low mass.
Custom Components and Special ShapesThe as-fired surface finish of sintered alpha SiC components is smooth, about 1 micrometer, reflecting its fine grain nature and high density. Using sintered alpha SiC, even the most intricate components can be manufactured to the most exacting specifications. The components can also be ground to tight tolerances.
With exceptional properties such as high temperature strength, oxidation resistance, creep resistance, thermal shock resistance and high thermal conductivity, sintered alpha SiC has been proven as an excellent alternative material to other ceramics, refractories and superalloys. It can provide a cost-effective solution for a wide range of high temperature applications in the ceramic industry.
For More InformationFor more information about sintered alpha SiC, contact John Bevilacqua at Saint-Gobain Advanced Ceramics, Structural Ceramics Group, 23 Acheson Drive, Niagara Falls, NY 14303; (716) 278-6022; or e-mail firstname.lastname@example.org.
*Hexoloy® SiC, a registered trademark of Saint-Gobain Advanced Ceramics, Structural Ceramics Group—formerly Carborundum Corp. **“Kiln Support Beams Increase Capacity,” Ceramic Industry, May 2000, pp. 16-18.